Source Characteristics Of VOC Emissions From Typical Industrial Painting Sources

In recent years, many city clusters in China have been facing the problem of regional complex air pollution characterized by high PM2.5 and O3 concentrations. As an important precursor of PM2.5 and O3, volatile organic compounds(VOCs) are closely related to secondary pollution and the industrial painting was one significant anthropogenic emission sources for it. Research on source characteristics and source profiles of VOCs emission from industrial painting are fundamental for understanding the regional complex air pollution since it can provide basic data for emission source indentificantion and air quality modeling, as well as guidance for control measures making.Characteristics of technical processes, consumption of raw and auxiliary materials as well astreatment techniques for typical painting industries were obtained through field investigation. Besides, VOCs removal characteristics and removal efficiencies of typical treatment techniques were also investigated via field monitoring. Based on that, typical painting industries including wood furniture manufacturing, automobile manufacturing, ship manufacturing, metal surface painting, plastic surface painting and fabric painting were selected to carry out field measurement. 95 source samples were collected by SUMMA canisters and analyzied by GC-FID-MSD to obtain the emission characteristics of these industries.Results showed that:(1) For industrial painting, VOCs are mainly derived from the use of organic raw materialin the process of painting and drying. The VOCs contents of un-prepared solvent-based coating, ready-to-use solvent-based coating, water-based coating and UV coating were about 20%~80%, more than 50%, 15% and 0%, respectively.(2) The removal efficiencies for activated carbon, activated carbon-water spray, activated carbon-adsorption concentration-catalytic oxidation, non-thermal plasmas, solution absorption and water spray- solution absorption were about-98.1%~79.2%,-167.4%~57.5%,-3.8%~66.5%,34.1%~96.3%,22.8%~43.1% and 2.7%~19.6%, respectively. Activated carbon and its combination techniques were not suitable for treating VOCs waste gas with concentrations less than 100mg/m3, while non-thermal plasmas had poor removal efficiencies with concentrations higher than 1000mg/m3.(3) Six typical industrial painting industries had similar source profile patterns with aromatics and OVOCs were the most abundant species. The specific VOCs components generally contained dimethyl benzene, toluene, ethyl-benzene, trimethyl-benzene, ethyl acetate and butyl acetate.(4) For the same industry using different solvents, VOCs species characteristics were similar when painting in the same substrate, but obviously distinct when painting in the different substrate.(5) Styrene was one of the most significant VOCs species for water-based coating used in metal surface painting with its mass percent more than 90%.(6) Aromatic was the main VOCs species in 5 typical process including prime paint drying, guide painting, guide paint drying, top painting and top paint drying. But drying process emitted more short-chain alkane and alkene species compared with painting process.